Pathogens such as bacteria, fungi, viruses, and bacterial spores are responsible for a plethora of human and animal ills, as well as contamination of food and biological and environmental samples. The first step in microbial infections of animals is generally attachment or colonization of skin or mucus membranes, followed by subsequent invasion and dissemination of the infectious microbe. The portals of entry of pathogenic bacteria are predominantly the skin and mucus membranes.
In particular, bacteria of the Bacillus genus form stable spores that resist harsh conditions and extreme temperatures. Contamination of farmlands with B. anthracis leads to a fatal disease in domestic, agricultural, and wild animals (See e.g., Dragon and Rennie, Can. Vet. J. 36:295 [1995]). Human infection with this organism usually results from contact with infected animals or infected animal products (See e.g., Welkos et al., Infect. Immun. 51:795 [1986]). Human clinical syndromes include a pulmonary form that has a rapid onset and is frequently fatal. The gastrointestinal and cutaneous forms of anthrax, although less rapid, can result in fatalities unless treated aggressively (See e.g., Franz et al., JAMA 278:399 [1997]; and Pile et al., Arch. Intem. Med. 158:429 [1998]). Bacillus anthracis infection in humans is no longer common due to effective animal controls that include vaccines, antibiotics and appropriate disposal of infected livestock. However, animal anthrax infection still represents a significant problem due to the difficulty in decontamination of land and farms. In addition, there is concern about human infection brought about by warfare and/or terrorist activities.
While an anthrax vaccine is available (See e.g., Ivins et al., Vaccine 13:1779 [1995]) and can be used for the prevention of classic anthrax, genetic mixing of different strains of the organism can render the vaccine ineffective (See e.g., Mobley, Military Med. 160:547 [1995]). The potential consequences of the use of Anthrax spores as a biological weapon was demonstrated by the accidental release of Bacillus anthracis from a military microbiology laboratory in the former Soviet Union. Seventy-seven cases of human anthrax, including 66 deaths, were attributed to the accident. Some anthrax infections occurred as far as 4 kilometers from the laboratory (See e.g., Meselson et al., Science 266:1202 [1994]). Genetic analysis of infected victims revealed the presence of either multiple strains or a genetically altered B. anthracis (See e.g., Jackson et al., Proc. Nat. Acad. of Sci. U.S.A. 95:1224 [1998]).
Additionally, other members of the Bacillus genus are also reported to be etiological agents for many human diseases. Bacillus cereus is a common pathogen. It is involved in food borne diseases due to the ability of the spores to survive cooking procedures. It is also associated with local sepsis and wound and systemic infection (See e.g., Drobniewski, Clin. Micro. Rev. 6:324 [1993]). Many bacteria readily develop resistance to antibiotics. An organism infected with an antibiotic-resistant strain of bacteria faces serious and potentially life-threatening consequences.
Examples of bacteria that develop resistance include Staphylococcus that often cause fatal infections, Pneumococci that cause pneumonia and meningitis; Salmonella and E. coli that cause diarrhea; and Enterococci that cause blood-stream, surgical wound and urinary tract infections (See e.g., Berkelman et. al., J. Infcet. Dis. 170(2):272 [1994]).
Although an invaluable advance, antibiotic and antimicrobial therapy suffers from several problems, particularly when strains of various bacteria appear that are resistant to antibiotics. In addition, disinfectants/biocides (e.g., sodium hypochlorite, formaldehyde and phenols) that are highly effective against Bacillus spores, are not well suited for decontamination of the environment, equipment, or casualties. This is due to toxicity that leads to tissue necrosis and severe pulmonary injury following inhalation of volatile fumes. The corrosive nature of these compounds also renders them unsuitable for decontamination of sensitive equipment (See e.g., Alasri et al., Can. J. Micro. 39:52 [1993]; Beauchamp et al., Crit. Rev. Tox. 22:143 [1992]; Hess et al., Amer. J. dent. 4:51 [1991]; Lineaweaver et al., Arch. Surg. 120:267 [1985]; Morgan, Tox. Path. 25:291 [1997]; and Russell, Clin. Micro. 3;99 [1990]).
Influenza A virus is a common respirator pathogen that is widely used as a model system to test anti-viral agents in vitro (See e.g., Karaivanova and Spiro, Biochem. J. 329:511 [1998]; Mammen et al., J. Med. Chem. 38:4179 [1995]; and Huang et al., FEBS Letters 291:199 [1991]), and in vivo (See e.g., Waghorn and Goa, Drugs 55:721 [1998]; Mendel et al., Antimicrob. Agents Chemother. 42:640 [1998]; and Smith et al., J. med. Chem. 41:787 [1998]). The envelope glycoproteins, hemagglutinin (HA) and neuraminidase (NA), which determine the antigenic specificity of viral subtypes, are able to readily mutate, allowing the virus to evade neutralizing antibodies. Current anti-viral compounds and neuraminidase inhibitors are minimally effective and viral resistance is common.
Clearly, antipathogenic compositions and methods that decrease the infectivity, morbidity, and mortality associated with pathogenic exposure are needed. Such compositions and methods should preferably not have the undesirable properties of promoting microbial resistance, or of being toxic to the recipient.